When US Secretary of State Condoleezza Rice alights from her plane in Sudan Wednesday, she'll look out across the dusty metropolis of the capital, Khartoum, onto a distinctly different national landscape from what her predecessor, Colin Powell, saw when he visited 13 months ago.

Since then, Sudan has elected a national unity government, penned a peace agreement with rebels in Sudan's troubled Darfur region, increased its flow of oil, and reinforced its status as a valuable partner in the US fight against global terrorism.

Ms. Rice's visit represents an acknowledgment of these changes - and that Khartoum is beginning to be "welcomed back into the civilized world, so to speak," says John Ashworth, a longtime Sudan observer with ties to South African church groups active in Sudan.

The July 9 inauguration of a new national-unity government in Khartoum represents another step in solidifying the end of Africa's longest civil war, which raged for 22 years between the government and southern rebels. Now the rebel leader is a vice president - and the new constitution expands religious and political rights.

On July 6, the government and rebels from the troubled Darfur region signed a "declaration of principles" - a small step toward peace. Observers say the north-south peace deal can be a template for Darfur, and a separate growing rebellion in the east.

Sudan's strategic value to the US is also far more evident. Since the north-south peace deal, oil exports have spiked. And an April trip to Washington by Sudan's intelligence chief - in a CIA jet - hints at how the US relies on Sudan in the war on terror. Africa's largest country, once home to Osama bin Laden, may still be a gathering point for terrorists.

While there has been much progress made, Mr. Ashworth stresses, the shifts hardly guarantee continued progress on issues like Darfur. It's crucial that the US and other outside powers continue to apply pressure, he says.

"What a lot of Western diplomats fail to realize," Ashworth says in a warning to Rice, is that throughout "the history of Sudan, all sorts of things have been agreed to; but what's written on paper is not always respected, to put it diplomatically."

In Darfur, for instance, the need for progress is great. The so-called "hungry season" is about to begin. That's the three-month period between planting and harvest. Some 3.5 million lives are at risk, according to the United Nations, although malnutrition levels are less severe than last year.

About 2 million people were forced to flee because of government-backed attacks on Darfur villages over the past two years. The African Union now has some 3,000 troops in place monitoring a much-ignored cease-fire between government and rebel forces. Talks based on the July 6 "declaration of principles" are set to resume in August.

Amid the continuing Darfur crisis, the US has maintained its sanctions on Sudan - and kept it on the "state sponsors of terror" list.

So Rice's trip is an opportunity for her to add "another level of pressure on Khartoum," even as it's a "high-level reward" for the changes they have already made, says Stephen Morrison of the Center for Strategic and International Studies in Washington.

Indeed, these shifts are leading to stirrings of hope that the country's fundamental political dynamic - which has led to decades of wars - may be starting to change. For years, Arab-Muslim elites have held most of the economic and political power, leaving the vast majority of people on the periphery - including in Darfur - with little. The wars all began when these marginalized groups rebelled.

Now power may be starting to devolve outward.

Under the north-south peace deal the government set up a model where the south will be "completely self-governing for six years, and in six years it could secede completely," explains Ashworth.

That's an anomaly in recent Sudanese history. But it does not guarantee the same will happen in Darfur and the east, warns David Mozersky of International Crisis Group in Nairobi. The north-south peace deal does not inherently "provide a solution for those areas," he says. Separate deals will have to be struck.

In Sudan's east, the Beja and other tribes have begun fighting for more economic and political power. They are not considered as militarily powerful as Darfur rebels. Yet they could cut key communications and supply routes from the country's major shipping facility at Port Sudan.

Overall changes to the country will occur slowly. The national unity government's new constitution, for instance, hardly creates an instant democracy. The ruling party now has a guaranteed 52 percent share of parliamentary seats. The former rebels - the Sudan People's Liberation Movement headed by First Vice President John Garang - get 28 percent. Northern and southern opposition parties share the remaining 20 percent.

If democracy does start to take hold in earnest, and if Darfur is resolved, US sanctions could eventually be lifted.

This would enable US companies to invest in the third-biggest oil industry in sub-Saharan Africa, after Nigeria and Angola. Output is expected to rise from about 340,000 barrels per day now to 500,000 per day in August. It could rise to 2 million per day in 2008. Oil fields in Darfur - where Chinese petroleum companies have a significant stake - should begin producing next year.

Meanwhile, Sudan is keen to be removed from the US State Department list of nations that sponsor terrorism and has reportedly been willing to share intelligence and even detain radicals who may have been on their way to Iraq.

Given all these elements, says Dr. Morrison, visits by Rice and other US officials may become regular events on the diplomatic calendar: "You're going to see a pattern of pretty regular passing through town by senior officials."